1. Technical Field
The present invention relates to an image-forming device including a cleaning unit for cleaning a belt.
2. Related Art
Japanese Patent No. 3,403,816 discloses an image-forming device including an image-carrying member on which a developer image is formed; an endless belt to which the developer image carried on the image-carrying member is transferred; and a cleaning unit for cleaning the endless belt. The cleaning unit cleans a portion of the belt which has a width equal to or slightly greater than a width of an effective image forming region on the image-carrying member. Here, the effective image forming region is provided on the image-carrying member on which an electrostatic latent image is formed, developed into a developer image, and transferred to the recording medium with a uniform quality, for forming an image on a recording medium. The effective image forming region is generally defined on the surface of the image-carrying member slightly inside both ends thereof in a widthwise direction.
In the image-forming device having this construction, the cleaning unit generally cleans developer on a region of the endless belt corresponding to the effective image forming region.
Generally, the above type of image-forming device has a developer-carrying member for supplying developer to the image-carrying member. The developer-carrying member normally carries a thin layer of developer on a thin film forming region on the outer surface thereof. The thin layer has a width which is greater than that of the effective image forming region.
The developer sometimes reaches the endless belt from the thin layer forming region. Therefore, a problem arises in that the conventional cleaning unit is not sufficient to clean the deposited developer on the endless belt.